TY - JOUR
T1 - NIHAO XVI
T2 - The properties and evolution of kinematically selected discs, bulges, and stellar haloes
AU - Obreja, Aura
AU - Dutton, Aaron A.
AU - MacCiò, Andrea V.
AU - Moster, Benjamin
AU - Buck, Tobias
AU - Van Den Ven, Glenn
AU - Wang, Liang
AU - Stinson, Gregory S.
AU - Zhu, Ling
N1 - Funding Information:
We thank the anonymous referee for helping us to improve the clarity of the manuscript. We would also like to thank Rosa Domínguez Tenreiro, Chris Brook, Fabrizio Arrigoni Battaia, and Roberto Decarli for useful discussions. This research was carried out on the High Performance Computing resources at New York University Abu Dhabi, on the THEO cluster of the Max-Planck-Institut für Astronomie and on the HYDRA clusters at the Rechenzen-trum in Garching. We greatly appreciate the contributions of these computing allocations. All figures in this work have been made with MATPLOTLIB (Hunter 2007). The GSF code uses PYNBODY (Pontzen et al. 2013) to load the simulations and SCIKIT-LEARN (Pedregosa et al. 2011) to run the clustering algorithm, as well as the PYTHON libraries NUMPY (Walt, Colbert & Varoquaux 2011) and SCIPY (Jones et al. 2001). F2PY (Peterson 2009) has been used to compile the GSF FORTRAN module for PYTHON. AO and BM have been funded by the Deutsche Forschungsgemeinschaft (DFG, German Research Foundation) – MO 2979/1-1. TB acknowledges support from the Sonderforschungsbereich SFB 881 ‘The Milky Way System’ (subproject A1) of the DFG. GvdV acknowledges funding from the European Research Council (ERC) under the European
Funding Information:
Union’s Horizon 2020 research and innovation programme under grant agreement No 724857 (Consolidator Grant ArcheoDyn).
Publisher Copyright:
© 2019 The Author(s).
PY - 2019/8/11
Y1 - 2019/8/11
N2 - We use 25 simulated galaxies from the NIHAO project to define and characterize a variety of kinematic stellar structures: Thin and thick discs, large-scale single discs, classical and pseudobulges, spheroids, inner discs, and stellar haloes. These structures have masses, spins, shapes, and rotational support in good agreement with theoretical expectations and observational data. Above a dark matter halo mass of 2.5 × 1011Mθ, all galaxies have a classical bulge and 70 per cent have a thin and thick disc. The kinematic (thin) discs follow a power-law relation between angular momentum and stellarmass J= 3.4M1.26±0.06, in very good agreement with the prediction based on the empirical stellar-to-halo-mass relation in the same mass range, and show a strong correlation between maximum 'observed' rotation velocity and dark matter halo circular velocity vc = 6.4v0.64±0.04 max . Tracing back in time these structures' progenitors, we find all of them to lose a fraction 1 - fj of their maximum angular momentum. Thin discs are significantly better at retaining their high-redshift spins (fj ∼ 0.70) than thick ones (fj ∼ 0.40). Stellar haloes have their progenitor baryons assembled the latest (z1/2 ∼ 1.1) and over the longest time-scales (τ ∼ 6.2Gyr), and have the smallest fraction of stars born in situ (fin situ = 0.35 ± 0.14). All other structures have 1.5 ≲ z1/2 ≲ 3, τ = 4 ± 2Gyr, and fin situ ≳ 0.9.
AB - We use 25 simulated galaxies from the NIHAO project to define and characterize a variety of kinematic stellar structures: Thin and thick discs, large-scale single discs, classical and pseudobulges, spheroids, inner discs, and stellar haloes. These structures have masses, spins, shapes, and rotational support in good agreement with theoretical expectations and observational data. Above a dark matter halo mass of 2.5 × 1011Mθ, all galaxies have a classical bulge and 70 per cent have a thin and thick disc. The kinematic (thin) discs follow a power-law relation between angular momentum and stellarmass J= 3.4M1.26±0.06, in very good agreement with the prediction based on the empirical stellar-to-halo-mass relation in the same mass range, and show a strong correlation between maximum 'observed' rotation velocity and dark matter halo circular velocity vc = 6.4v0.64±0.04 max . Tracing back in time these structures' progenitors, we find all of them to lose a fraction 1 - fj of their maximum angular momentum. Thin discs are significantly better at retaining their high-redshift spins (fj ∼ 0.70) than thick ones (fj ∼ 0.40). Stellar haloes have their progenitor baryons assembled the latest (z1/2 ∼ 1.1) and over the longest time-scales (τ ∼ 6.2Gyr), and have the smallest fraction of stars born in situ (fin situ = 0.35 ± 0.14). All other structures have 1.5 ≲ z1/2 ≲ 3, τ = 4 ± 2Gyr, and fin situ ≳ 0.9.
KW - Galaxies: Fundamental parameters
KW - Galaxies: Kinematics and dynamics
KW - Galaxies: Stellar content
KW - Galaxies: Structure
KW - Methods: numerical
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U2 - 10.1093/mnras/stz1563
DO - 10.1093/mnras/stz1563
M3 - Article
AN - SCOPUS:85072267770
VL - 487
SP - 4424
EP - 4456
JO - Monthly Notices of the Royal Astronomical Society
JF - Monthly Notices of the Royal Astronomical Society
SN - 0035-8711
IS - 3
ER -